1. Field of the Invention
This invention relates to novel polymerizable acyl imidazolidinones, their preparation and their utility in preparing self-crosslinking polymers and latices thereof. The polymerizable monomers of the present invention are also useful in paper and textile applications and in improving wet adhesion properties of latex paints.
2. Description of Related Art
It is well-known in the art to employ self-crosslinking polymers, either in emulsion or solution form, as coatings, binders or adhesives for a variety of substrates. Self-crosslinking polymers are distinguished from crosslinkable polymers in that the latter contain functionality such as a carboxyl group which can only be crosslinked by the addition of an external crosslinker to the polymer emulsion or solution. A typical crosslinkable system is a poly(carboxyl functional) polymer crosslinked with a polyepoxy crosslinker.
In contrast, self-crosslinking polymers contain reactive functionalities which allow these polymers to self-crosslink without the need for an external crosslinking agent. A typical crosslinking polymer containing N-methylolated amide functionalities, incorporated via N-methylolacrylamide, undergoes thermosetting crosslinking by splitting out a mole of formaldehyde. The advantages of the self-crosslinking polymer systems include their simplicity, economy, and particularly their efficiency. Such systems have been used in a variety of applications, including use as textile adhesives, nonwoven binders, pigment binders, fabric finishing agents, binders for paper and wood finishing applications.
Interior and exterior latex-based paints exhibit poor wet adhesion compared to solvent-based paints. The term wet adhesion is used in the paint industry to describe the ability of a paint to retain its adhesive bond to a substrate under wet or high humidity conditions. While oil-based systems are known to retain their adhesive properties under wet or humid conditions, the tendency of many water based coatings (i.e., latices) to lose their adhesive properties when wet has limited the usefulness of such coatings. The wet adhesion deficiency of latex paints also makes surfaces painted with such paints less scrub resistant than those surfaces painted with organic solvent based paints.
Since the use of water-based emulsion polymer systems as protective and decorative coatings for many types of surfaces has become widespread, such systems being used by individuals in homes and industrially, there is a great need for improved wet adhesion of aqueous emulsion polymer systems. In recent years, the art has recognized the problem of loss of adhesive properties in latex paints and a variety of additives to latex systems to improve wet adhesion have been proposed. Incorporation of amine, amide, acetoacetate, urea and ureido functionalities into latex polymers has been reported to improve the wet adhesion properties of latex paints. For example, an imidazolidinone compound (cyclic ureido) has been described in EP-A-0629672 as imparting wet adhesion properties to various latex systems, which reference is incorporated by reference herein for all purposes as if fully set forth.
U.S. Pat. Nos. 4,577,031, 4,596,850 and 4,622,374, and EP-A-0629672, specifically disclose polymerizable imidazolidinones and their use as self-crosslinking monomers which also improve the wet adhesion properties of latex paints. However, the self-crosslinking and wet adhesion promoter monomers of the aforementioned prior art have the disadvantage that they are expensive and their inclusion into latex polymers results in substantial increase in the final cost of latex-based paints.
It has now been found that self-crosslinking and wet-adhesion properties can be imparted to latex-based polymers and paints produced from such polymers by incorporating into the monomer system, from which the polymers are produced, one or more of the present invention's new class of acyl imidazolidinones. A unique advantage of the present invention's new class of compounds is that they can be made from inexpensive and readily obtainable raw materials, including urea, maleic anhydride and hydroxy and amino functional coreactants. Other suitable anhydrides from which the invention's new class of compounds can be made include citraconic anhydride and itaconic anhydride.
It has also been discovered that the novel higher alkyl esters and amides of the acyl imidazolidinones also provide sizing properties to paper and textiles. They can, therefore, be used as alternatives to sizing agents such as ACCOSIZE.RTM. 17 (Cytec Industries) and other paper treating agents, as, for example, those compounds disclosed in U.S. Pat. No. 2,727,016, which is herein incorporated by reference for all purposes as if fully set forth.